The effect of atomic binding on a nuclear resonance

A recent analysis of a sharp (γ ≈ 1.6 keV) resonance in the ¹²C(p,p)¹²C reaction interprets 0.6 keV of the width as an atomic effect associated with excitation of the final atom. We describe a simpler, almost kinematic, atomic effect, viz. the smearing of the relative velocity of incident proton and target nucleus by the velocity distribution of the nucleus in the initial atom. While reproducing about the same broadening, this approach differs from the previous one in all other aspects.